Continuous distal migration and internal rotation of the C-stem prosthesis without any adverse clinical effects: an RSA study of 33 primary total hip arthroplasties followed for up to ten years.

In 2005, we demonstrated that the polished triple-tapered C-stem at two years had migrated distally and rotated internally. From that series, 33 patients have now been followed radiologically, clinically and by radiostereometric analysis (RSA) for up to ten years. The distal migration within the cement mantle had continued and reached a mean of 2 mm (0.5 to 4.0) at ten years. Internal rotation, also within the cement mantle, was a mean 3.8° (external 1.6° to internal 6.6°) The cement mantle did not show any sign of migration or loosening in relation to the femoral bone. There were no clinical or radiological signs indicating that the migration or rotation within the cement mantle had had any adverse effects for the patients.

Total hip replacement with a zirconium oxide ceramic femoral head: a randomised roentgen stereophotogrammetric study.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26). At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision. Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

Destructive knee joint infection caused by Peptostreptococcus micros: importance of early microbiological diagnosis.

Peptostreptococcus micros is a commensal of the oral cavity and the genitourinary tract that rarely causes serious infections. A case of a destructive knee joint infection with rapid progress caused by P. micros is presented. The significance of the microbiological findings was initially not acknowledged, which contributed to a nonsuccessful clinical outcome.

Bacteriologic evidence of infection caused by coagulase-negative staphylococci in total hip replacement.

Coagulase-negative staphylococci are important agents of infected hip arthroplasties, but sample contamination from the skin flora may confuse the diagnosis. Recovery of multiple identical strains has been regarded as indication of true infection. We have evaluated 29 total hip replacement operations with cultures positive for coagulase-negative staphylococci in a prospective study, 16 with > or = 3 isolates available for strain identity analysis. In 26 episodes, > or = 3 cultures were positive for coagulase-negative staphylococci, but only 19 of them had strong or intermediate clinical evidence of infection. Negative clinical evidence of infection coincided with the absence of a predominating strain according to plasmid profile analysis. A reliable identity analysis may help to rule out infection when multiple cultures are positive in patients who lack clinical evidence of infection.

Periprosthetic low-grade hip infections. Erythrocyte sedimentation rate and C-reactive protein in 23 cases.

We followed 23 patients from the primary total hip arthroplasty to revision for a bacteriologically proven deep infection with a low virulent organism. The median time to revision was 14 (4-65) months. During this period, the maximum ESR value was median 50 (22-110) mm and the maximum CRP value was 35 (9-95) mg/L. 25 of the 98 CRP values recorded were normal (< 9 mg/L) and 22/89 ESR values were below 30 mm/h. In 6 patients, all CRP values were below 20 mg/L, but 5 of these patients had an ESR > 30 mm. Before the revision, normal values for both tests were found in only 1 patient. Both normal values and slight-to-moderate increases in ESR and/or CRP are consistent with a low-grade periprosthetic hip infection. We recommend that ESR should be determined preoperatively in all patients scheduled for total hip replacement to establish a baseline.

Total knee arthroplasty after failed proximal tibial valgus osteotomy.

The results of total knee arthroplasty were evaluated in 113 patients with gonarthrosis (14 patients with and 99 without prior operation with proximal tibial valgus osteotomy). There was no difference in the final result after follow-up periods of 4-9 years with respect to average Hospital for Special Surgery score. degree of knee flexion, and later knee revisions between the 14 osteotomized and 99 nonosteotomized patients. The average femorotibial angle did not differ between the groups; neither did the average wear of the tibial polyethylene. No difference was found in operative time, but a significantly greater blood loss and other postoperative complications were noted among the previously osteotomized group of patients, indicating a more complicated procedure for the knee arthroplasty operation compared with the nonosteotomized group of patients.

The prognosis and treatment of dislocated total hip arthroplasties with a 22 mm head.

We studied the risk of recurrent dislocation in 121 primary and 39 revision Charnley or Charnley hybrid total hip arthroplasties which had been treated for a primary dislocation between 1979 and 1995. Only 35% of these hips had no further dislocation or a revision for instability within one year. The rates of survival gradually declined with time or if a second, third or fourth dislocation occurred. The risk of recurrence was greater in men, but was not related to age, diagnosis, time of the first dislocation or whether the index operation had been a primary or a revision procedure. Operative treatment included 15 reoperations leaving intact components, 50 revisions, and permanent removal of the femoral stem in seven patients. The operation was successful in four patients with reoperations and in 36 who had an exchange procedure within two years. Treatment was successful in 35 of 49 hips in which it was possible to correct a technical error compared with 5 out of 16 hips in which malposition of the components was not seen (p = 0.007).

Radiographic wear assessment in a total knee prosthesis. 5- to 9-year follow-up study of 158 knees.

One hundred fifty-eight Porous-Coated Anatomic (Howmedica, Rutherford, NJ) primary total knee prostheses were evaluated clinically and radiographically to measure the remaining thickness of the plastic insert. Anteroposterior radiographs were taken with the beam guided parallel to the tibial plate by a fluoroscope. The knees were forced into varus and valgus, and the heights of the medial and lateral joint spaces, respectively, were measured with a digitizing table. Plastic insert wear could be calculated after correction with a magnification error factor, established by dividing the projected width of the tibial plate by the true size of the used component. After a mean follow-up period of 84 months (range, 58-116 months), wear was significantly higher for patients with osteoarthritis than rheumatoid arthritis and was 1.4 mm versus 0.7 mm medially (P < .0001) and 0.7 mm versus 0.4 mm laterally (P = .01). Wear was not correlated to thickness of the plastic insert or length of follow-up period. Young age or varus alignment contributed slightly to the amount of wear.

Total hip replacement in patients with hemophilia. 13 hips in 11 patients followed for 1-16 years.

During 1973-88, we performed 13 total hip replacements in 11 hemophilia patients, mean age 46 (25-65) years. During the operation, blood loss averaged 920 mL, and a mean of 120,000 units of factor VIII/IX were used. The mean duration of follow-up was 7 (1-16) years. 5 hips became loose within 6 years, and a further one after 13 years. 4 hips were revised, 2 of them due to infection in patients who were also seropositive for HIV. At the latest follow-up, 10 patients were alive. 6 had no hip pain and 7 could walk at least 1,000 meters at a time. Although these results are inferior to those obtained in arthrosis, total hip replacement should be considered in hemophiliac patients.

Migration and wear of a hydroxyapatite-coated hip prosthesis. A controlled roentgen stereophotogrammetric study.

A consecutive series of 30 total hip replacements using a hydroxyapatite (HA)-coated, modular implant (Omnifit) was followed clinically and by roentgen stereophotogrammetric analysis for two years and compared with two control groups, one of 27 cemented Charnley sockets and one of 40 cemented Charnley stems. Omnifit sockets with a central gap between the dome of the socket and the acetabular bone in the postoperative radiographs, migrated less than sockets without such gaps (p = 0.01). After adjustment for patient-related factors (age, gender and weight), no significant difference was found between the two prostheses with respect to micromotion and wear. We conclude that the early fixation of the HA-coated Omnifit prosthesis compares with that of the cemented Charnley prosthesis.

Infection adjacent to titanium and bone cement implants: an experimental study in rabbits.

A pure titanium cylinder or a piece of bone cement was implanted in each upper tibial metaphysis of 20 rabbits. After 4 months radiograms were taken and 10(4), 10(6), or 10(8) Staphylococcus aureus were injected into each leg through central holes in the implants in three groups of animals. Four weeks later new radiograms, bacteriological and histological biopsies were obtained. Three animals died before the end of the experiment. In animals which received 10(6) or 10(8) S. aureus radiographic signs of infection were found in 11/22 legs with both titanium and bone cement implants. No radiolucent zones developed around the implants. Bacteriological cultures from bone close to the implants were negative in all legs with titanium implants and positive in four legs with cement implants. Seven cultures were negative in spite of radiographic changes. It is concluded that after a proper time for wound healing the bone around unloaded implants of both titanium and bone cement is fairly resistant to infection. In some cases, healing of an infection in the surrounding bone seems possible.

Migration of uncemented, long-stem femoral components in revision hip arthroplasty. A 2-8 year clinical follow-up of 45 cases and radiostereometric analysis of 13 cases.

We reviewed after 48 (24-90) months the clinical results in 45 cases of revision hip arthroplasties where an uncemented, long-stem femoral prosthesis (BIAS, Zimmer) had been used. A subgroup of 13 cases was followed with radiostereometric analysis (RSA) for 2 years. 3/45 cases had been revised, another 12 had unsatisfactory pain scores. The median Harris score was 69 (26-99). 12/13 stems migrated; 11 subsided 4.1 (0.4-7.9) mm, and 8 migrated posteriorly 2.9 (1.9-9.6) mm. The poor clinical results and large migrations speak against the use of this prosthesis in revision hip arthroplasty.

Total hip arthroplasty in high congenital dislocation. 21 hips with a minimum five-year follow-up.

Total arthroplasty was performed on 21 congenitally dislocated hips in 18 women. In all cases the femoral head was dislocated cranially at least one-fifth of the height of the pelvis. The components were both cemented, the acetabulum being replaced to its original position. The acetabular roof was reconstructed by bone graft in 13 hips, and trochanteric osteotomy was done in 18 hips. The patients were assessed at a median follow-up time of 7.5 years when their median age was 54 years. Nine patients had been revised or required revision. At follow-up the average functional score (according to Charnley) was 6 for pain, 4 for walking ability and 5 for range of motion. The Harris hip score was 82. The patients' subjective evaluation of their satisfaction with the late results on a visual analogue scale was 93, range 23 to 100. The high loosening rate in such patients demands regular follow-up and preparedness for revision surgery.

Air contamination during total hip arthroplasty in an ultraclean air enclosure using different types of staff clothing.

Air contamination was measured in a down-flow, clean air enclosure during 50 total hip arthroplasties to compare the effect of different scrub suits and operating gowns. In one series, with cotton clothes, the operating gowns used were either disposable nonwoven operating gowns or total body exhaust gowns. With the exhaust gowns the median air contamination, measured as colony-forming units (cfu)/m3, was reduced by about 5 times, to 0.3. In another series, nonwoven operating gowns were used together with scrub suits made of either cotton or one of two types of synthetic materials. The latter two scrub suits were equipped with elastic sealings at the openings. With both of these types the median air contamination, compared to cotton scrub suits, was reduced by about one half, to 0.4 cfu/m3. The authors conclude that both specially designed scrub suits and exhaust gowns can further reduce an already low level of bacterial air contamination in a down-flow, clean air enclosure.

Hip arthroplasty infection. Current concepts.

Due to systemic or local antibiotic treatment and other preventive procedures, the incidence of deep hip-prosthetic infections in Scandinavia is less than 1 percent, with the majority hematogenous. Coagulase-negative staphylococci and anaerobes are involved in more than half of the cases. The diagnosis is sometimes difficult; preoperative aspiration often gives misleading results; and granulocyte scanning usually adds valuable information. In deep infection the current strategy is to revise with a two-stage procedure. Revisions should be carried out at specialized centers with bacteriologic competence and sufficient experience with implants.

Occlusive clothing and ultraviolet radiation in hip surgery.

In a randomized study of 20 total hip arthroplasties, the staff wore shirts and trousers of a fabric impervious to bacteria underneath operating gowns of a non-woven material. Volumetric air sampling demonstrated a low number of colony-forming units with this clothing, further reduced by ultraviolet radiation to below 10 colony-forming units/m3, the upper limit of "ultraclean air," in all the cases (median 2.6, range 1.1-7.1).